Conventionally, hydrofluorocarbon (HFC) based refrigerants have been used as the refrigerants for heat pump devices or refrigerating machines. HFC refrigerants have an ozone depletion potential of zero, and have superior thermal stability. On the other hand, HFC refrigerants have an extremely high global warming potential (GWP) of several hundred to several thousand. As a result, the use of HFC refrigerants is undesirable from the viewpoint of protecting the global environment.
Examples of known refrigerants having a low GWP include hydrofluoroolefin (HFO) based refrigerants and hydrochlorofluoroolefin (HCFO) based refrigerants. In Patent Literature 1, tetrafluoropropene (HFO1234) is used as an HFO refrigerant.